Background:
Vascular air embolism (VAE) during bronchoscopy is a rare but serious complication. Presentation depends on the volume and rate of gas infusion, and can range from clinically undetectable to cardiovascular collapse. Neurological manifestations may arise from arterial or paroxysmal emboli, or be secondary to hypoperfusion. Even though considered a safe procedure, bronchoscopy implicates several risk factors for VAE, such as sitting position, pressure gradient and air inflation.

Case Report:
A 19 year old female with stage IV Hodgkin lymphoma underwent flexible bronchoscopy under sedation with propofol. A lung biopsy was performed, followed by air installation (120mL) and lavage with saline. Simultaneously, an episode of desaturation and bradycardia was treated with supplemental O2 and atropine. At the end of the procedure, the patient was hemodynamically stable but unconscious. Pupils were isochoric and reactive, decerebrate movements were elicited by painful stimuli and spontaneous but irregular breathing required intubation and assisted ventilation. Blood gas analysis was normal. Brain CT revealed cortical air emboli and infarctions. Hyperbaric oxygen therapy (HBOT) was initiated 8h after the event and repeated the next day. Due to neurological deterioration with diffuse cerebral edema, the patient died at day 3.

Discussion:
Although mechanisms are unclear, we speculate that high bronchial pressure and trauma to a necrotic lesion resulted in air entering pulmonary veins, then left heart and cerebral vessels. Since the patient was sedated and clinically stable, neurological signs were recognized only at the end of the procedure. A high level of suspicion is crucial for early recognition and prevention of further air entry. While a drop in end tidal CO2 may be an early sign, precordial doppler is a more sensitive non-invasive method. A possible benefit for HBOT has been suggested for treatments in the first 6 hours, as a high O2 blood content might reduce the size of air emboli and subsequent ischaemia. However, brain infarcts on the first CT carry a poor prognosis.

02 / Unresponsive patient after flexible bronchoscopy - a fatal case of cerebral air embolism